Useless customer agent

So MTN decided to change my payment terms from debit order to cash without informing. I only found out after I contacted them that there were changes. Funny thing is I never instructed this change and no one seems to have any answers. I called yesterday and well, the contact centre was just useless. I then emailed and it seems like no one is reading my emails as their answers are not answering the questions I have asked. This has been such an inconvenience. And I am really disappointed at how helpful your agents are. Very disappointed customer